Ticks and tick-associated pathogens of livestock in remote villages of central South Sudan

Dr. Johnson has conducted animal health care workshops for the past 7 years in East Africa, where there is very little veterinary service or infrastructure. Based upon anecdotal reports and personal experience, there appear to be recent changes in the distribution of ticks and their associated diseases in South Sudan. However, we could not identify any surveys of ticks from livestock in these remote areas or reports of PCR testing of ticks from Sudan. Ticks were collected from cattle in Western and Central Equatoria, South Sudan, during veterinary outreach missions in April 2010, 2011, and 2012. The 356 ticks included 164 adult Amblyomma variegatum and 39 Amblyomma nymphs; 115 adult Rhipicephalus appendiculatus; 1 male R. praetextatus; 7 R. (Boophilus) annulatus; 29 R. (Boophilus) decoloratus, and 1 male Hyalomma rufipes. Although A. variegatum were collected from every site, there was significant site-to-site variation in the presence of R. appendiculatus and R. decoloratus. A subset of 124 ticks was selected for DNA extraction and pathogen screening using PCR and sequencing. Overall, 79 (64%) contained evidence of one or more tick-borne pathogens. Anaplasmataceae were the most abundant, with DNA found in 13.5% of A. variegatum, 73% of R. appendiculatus, 75% of R. annulatus, and 58% of R. decoloratus; sequence analysis is underway to identify taxa of Anaplasma and Ehrlichia. Rickettsia africae was detected in 56% of A. variegatum; Rickettsia were not seen in other ticks. Theileria mutans was detected in 2 A. variegatum and 1 engorged female R. decoloratus, Babesia bigemina in 1 R. decoloratus, and a Babesia caballi-like organism in 1 A. variegatum. Although local reports indicate that R. appendiculatus has recently expanded its range into Western Equatoria, and East Coast Fever (Theileria parva) is of significant concern, our data suggests that unrecognized infections with Anaplasmataceae could be a significant burden to livestock production in this area.